diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index fbe0112..5e9a5d4 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -12,11 +12,15 @@ jobs:
   build:
     strategy:
       matrix:
-        php: ['8.0', '8.1', '8.2']
-        phpunit: ['8.0', '9.0', '10.0']
+        php: [8.1', '8.2', '8.3', '8.4']
+        phpunit: ['8.0', '9.0', '10.0', '11.0', '12.0']
         exclude:
-          - php: '8.0'
-            phpunit: '10.0'
+          - php: '8.1'
+            phpunit: '11.0'
+          - php: '8.1'
+            phpunit: '12.0'
+          - php: '8.2'
+            phpunit: '12.0'
     runs-on: ubuntu-latest
     name: PHP ${{ matrix.php }}, PHPUnit ${{ matrix.phpunit }}
 
diff --git a/.github/workflows/php_coverage.yml b/.github/workflows/php_coverage.yml
index d9e154b..20705e4 100644
--- a/.github/workflows/php_coverage.yml
+++ b/.github/workflows/php_coverage.yml
@@ -14,7 +14,7 @@ jobs:
     - name: Setup PHP
       uses: shivammathur/setup-php@v2
       with:
-        php-version: 8.0
+        php-version: 8.1
         extensions: mbstring, intl, json
         coverage: pcov
 
diff --git a/README.md b/README.md
index 618d465..ece33b7 100644
--- a/README.md
+++ b/README.md
@@ -24,12 +24,12 @@ There are several release branches of this library, each of these being compatib
 with different releases of PHPUnit and PHP. The following table should give an
 easy overview:
 
-| PSR-7 assertion version | PHPUnit 4 | PHPUnit 5 | PHPUnit 6 | PHPUnit 7 | PHPUnit 8 | PHPUnit 9 | PHPUnit 10 |
-| ----------------------- | --------- | --------- | --------- | --------- | --------- | --------- | ---------- |
-| v1 (branch `v1`), **unsupported** | :white_check_mark: | :white_check_mark: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: |
-| v2 (branch `v2`), **unsupported** | :no_entry_sign: | :no_entry_sign: | :white_check_mark: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: |
-| v3 (branch `v3`), **unsupported** | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :white_check_mark: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: |
-| v4 (branch `master`) | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :white_check_mark: | :white_check_mark: | :white_check_mark: |
+| PSR-7 assertion version | PHPUnit 4 | PHPUnit 5 | PHPUnit 6 | PHPUnit 7 | PHPUnit 8 | PHPUnit 9 | PHPUnit 10 | PHPUnit 11 | PHPUnit 12 |
+| ----------------------- | --------- | --------- | --------- | --------- | --------- | --------- | ---------- | ---------- | ---------- |
+| v1 (branch `v1`), **unsupported** | :white_check_mark: | :white_check_mark: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: |
+| v2 (branch `v2`), **unsupported** | :no_entry_sign: | :no_entry_sign: | :white_check_mark: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: |
+| v3 (branch `v3`), **unsupported** | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :white_check_mark: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: |
+| v4 (branch `master`) | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :no_entry_sign: | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: |
 
 When you are using `composer require` and have already declared a dependency to
 `phpunit/phpunit` in your `composer.json` file, Composer should pick latest
diff --git a/composer.json b/composer.json
index 61813ae..1a3bd03 100644
--- a/composer.json
+++ b/composer.json
@@ -9,17 +9,17 @@
         }
     ],
     "require": {
-        "php": "^8.0",
+        "php": "^8.1",
         "helmich/phpunit-json-assert": "^3.4",
         "psr/http-message": "^1.1 || ^2.0"
     },
     "require-dev": {
         "guzzlehttp/psr7": "^2.4",
         "mockery/mockery": "^1.4.1",
-        "phpunit/phpunit": "^8.0 || ^9.0 || ^10.0"
+        "phpunit/phpunit": "^8.0 || ^9.0 || ^10.0 || ^11.0 || ^12.0"
     },
     "conflict": {
-        "phpunit/phpunit": "<8.0 || >= 11.0"
+        "phpunit/phpunit": "<8.0 || >= 13.0"
     },
     "autoload": {
         "psr-4": {